A pilot study: use of fludarabine for refractory dermatomyositis and polymyositis, and examination of endpoint measures

To study the effects of the adenine analog, fludarabine, on patients with refractory dermatomyositis and polymyositis, and to assess variables used in following myositis patients during medical intervention.

Patients whose myositis was not controlled by prednisone and at least one other immunosuppressive medication were entered into a pilot study during which they received 6 monthly cycles of intravenous fludarabine. Patients were assessed at baseline, every other month, and at month 7 for primary outcome measures of strength and function. Other measurements including peripheral blood cell subsets, muscle enzymes, and various assessments of disease activity were followed monthly during the fludarabine infusion period and for up to 6 months post therapy.

Of 16 patients who entered the study, 4 patients were classified as improved, and 7 patients were classified as unchanged. Five patients who withdrew before month 7 were classified as treatment failures. Fludarabine caused a significant and prolonged lymphopenia without an increase in infectious complications over that seen with other immunosuppressive agents used for myositis. A sudden death of one patient at the end of the study was not thought to be drug related. Variables followed during the study emphasized the distinction between patient functional improvement and disease remission.

A subset of patients with refractory myositis may benefit from fludarabine therapy and controlled trials are indicated. Refinement and validation of variables useful for following myositis patients await larger studies.